1. Field of the Invention
This invention relates to communications networks and particularly but not exclusively to networks known in the art at TPON networks. TPON is an acronym for Telephony over Passive Optical Network.
2. Related Art
A TPON network has been developed by the assignee of the present application and is described in the article "The provision of telephony over passive optical networks" by Hoppitt, C. E. and Clarke, D. E. A., British Telecom Technology Journal, Vol. 7, No. 2, pp 101-114 April, 1989. The signals from the different outstations, or network terminations, are bit-interleaved in the upstream multiframe, and correspondingly in the downstream multiframe. The outstations have separate transmitters and receivers, and thus it is possible for an outstation to transmit traffic signals at allocated channels in the upstream multiframes at the same time that it receives signals from the downstream multiframes.
In such a TPON network it would not be a simple matter to employ a transceiver, i.e. a single transducer for both functions, in an outstation. The central station, or head-end, would need to compute for each bit transmitted to each outstation which bits in the upstream multiframe would correspond to a transmit/receive conflict, i.e. that (a) the outstation was required to transmit at the same time as it was receiving, or (b) that the outstation was required to receive a bit before recovering from transmission of a bit to the central station. The allocations of the bit positions in the downstream and upstream multiframes for communications between the central station and an outstation would be determined by the results of the respective computation by the central station.